A few years ago, my truck started knocking and pinging on hills. Then I put some fuel additive in the gas tank and it went away for a while. When it came back, I started using medium octane gas, and that helped for a while. Now, it’s knocking more than ever–on hills and even on take off from a dead stop. Is there a danger of doing damage to my engine using high octane gas?
Using high octane gas, no. I would suggest that the EGR system might be getting clogged up causing the knocking.